From King Dictionary of Contemporary English
Related topics: Textures, sounds
thwackthwack /θwæk/ noun [countable] CSSOUNDa short loud sound like something hitting a hard surfacethwack verb [transitive]
Examples from the Corpus
thwackThe customary thwack on the bottom is still the best method for determining doneness.He hit the flaring log such a hefty thwack that it broke in two.From the next room came the thwack of darts and a louder hubbub of voices.Rely more on the thwack than the look.Somebody had procured an aluminum bat, and the traditional thwack surrendered to a whistling hum.
Origin thwack (1500-1600) From the sound